• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Wiring Help

  • Thread starter Thread starter Soup5915
  • Start date Start date Nov 1, 2021
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 1, 2021
#1
  • Nov 1, 2021
  • #1
Hello all. I’m new to the forum and I have searched everywhere for this info but can’t find anything so I figured I’d ask the pros. I purchased an 87 GT Vert a little over a month ago and working on getting it on the road for the spring. The car sat for three years and ALL the weather stripping is shot and the interior needs a refresh. I took the dash out , and the previous owner shredded the wiring, looks like spaghetti. I took out the remainder of an alarm system and parts of a sound system, but I have these 4 connectors that I do not know what they are. The two bigger plugs are under the drivers side, left of the steering column, I believe the yellow one is something for the 4cyl LX. The other two are just to the left of the heater box. Any help is greatly appreciated. Thanks.
 

Attachments

  • 63857A7C-430A-46DF-B32E-F00DB60B11D3.webp
    406.4 KB · Views: 156

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,164
17,860
224
Massachusetts
Nov 1, 2021
#2
  • Nov 1, 2021
  • #2
Big yellow one is 4cyl fan relay. Just ignore that. Other one connects to cruise control box in the background.


For the smaller two plugs. The one with the red/green stripe wires connects to the clutch switch on the quadrant side of the pedal box. It’s to disengage the cruise. Needs to be connected or have a jumper installed.

Other one escapes me at the moment. Too many beers
 
Reactions: 7991LXnSHO
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 1, 2021
#3
  • Nov 1, 2021
  • #3
Mustang5L5 said:
Big yellow one is 4cyl fan relay. Just ignore that. Other one connects to cruise control box in the background.


For the smaller two plugs. The one with the red/green stripe wires connects to the clutch switch on the quadrant side of the pedal box. It’s to disengage the cruise. Needs to be connected or have a jumper installed.

Other one escapes me at the moment. Too many beers
Click to expand...
Thank you. I ignored the yellow connector and plugged in the grey connector to the cruise control. As for the red/green wire connector I don’t see were this goes. I see a switch attached to the clutch but there are two plugs already there also this cable would not reach over there from where it comes out of the main harness bundle. And still no idea on the other plug.
 
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 1, 2021
#4
  • Nov 1, 2021
  • #4
Soup5915 said:
Thank you. I ignored the yellow connector and plugged in the grey connector to the cruise control. As for the red/green wire connector I don’t see were this goes. I see a switch attached to the clutch but there are two plugs already there also this cable would not reach over there from where it comes out of the main harness bundle. And still no idea on the other plug.
Click to expand...
Ok. I found the connection to the red/green wire connector. One more to go!!!
 
Reactions: Mustang5L5

manicmechanic007

5 Year Member
Sep 26, 2017
2,524
709
143
Roy, Utah
Nov 2, 2021
#5
  • Nov 2, 2021
  • #5
I agree with the above posts
There are plugs that do not go to anything unless you have the option for it
Fog lights for example
Same with air bags
The wiring was there before the bags were
Hence the Aerostar Lawsuit in '86 or?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,164
17,860
224
Massachusetts
Nov 2, 2021
#6
  • Nov 2, 2021
  • #6
What are the wire colors on the final plug? I can check my EVTM in a bit. I think I know what it is but want to confirm first
 
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 2, 2021
#7
  • Nov 2, 2021
  • #7
Mustang5L5 said:
What are the wire colors on the final plug? I can check my EVTM in a bit. I think I know what it is but want to confirm first
Click to expand...
In looking at the three wires its — blue/yellow — black/white — black/white
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,164
17,860
224
Massachusetts
Nov 2, 2021
#8
  • Nov 2, 2021
  • #8
Looked on my ‘88. That particular connector is not plugged in. However, my car is a hatchback. Unsure of that plug would be connected on a vert or 4cyl.

I can check my diagrams later
 
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 2, 2021
#9
  • Nov 2, 2021
  • #9
Mustang5L5 said:
Looked on my ‘88. That particular connector is not plugged in. However, my car is a hatchback. Unsure of that plug would be connected on a vert or 4cyl.

I can check my diagrams later
Click to expand...
Thanks, I really appreciate the information. If you don’t mind I did find another plug that has no home. It comes out of the main harness with the left side cluster plug as well as the flasher relay and dimmer switch. It’s odd shaped plug with 5 wires.
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,524
709
143
Roy, Utah
Nov 2, 2021
#10
  • Nov 2, 2021
  • #10
Looks like a rear window defroster latching relay connector
Could be any other old style relay like a horn relay
The pigtail is taped tight to the harness so I think the car did not have that particular option
Some plugs the factory uses to fire systems up
It could be one of those
 
Reactions: Soup5915

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,164
17,860
224
Massachusetts
Nov 3, 2021
#11
  • Nov 3, 2021
  • #11
That is the plug for the rear window defrost relay.

Since you have a convertible, it’s not used and should be empty.
 
Reactions: Soup5915
S

Soup5915

Member
Nov 1, 2021
7
1
13
New Hampshire
Nov 3, 2021
#12
  • Nov 3, 2021
  • #12
Mustang5L5 said:
That is the plug for the rear window defrost relay.

Since you have a convertible, it’s not used and should be empty.
Click to expand...
Thank you so much for all the info. Now that all the extra wires have been removed and all the plugs are accounted for its time to check all connections to make sure that all accessories/lights are working. Thanks again.
 

Dan02gt

mazing how much gas smell came from that tiny hole
20+ Year Stangneter
Mar 2, 2003
909
415
113
Greenville, NC
Nov 3, 2021
#13
  • Nov 3, 2021
  • #13
Soup5915 said:
In looking at the three wires its — blue/yellow — black/white — black/white
Click to expand...
I think that is the plug connects to the clutch switch for the neutral sensing system. The neutral sensing system tells the computer when the car is in gear or not and if the clutch is pressed in or not. This is so the computer can try to prevent stalling.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,164
17,860
224
Massachusetts
Nov 3, 2021
#14
  • Nov 3, 2021
  • #14
Dan,

That plug is on the left hand side of the pedal box. This one is on the right side. I’m also familiar with the plug you speak of and it looks different than this
 
You must log in or register to reply here.

Similar threads

F
Electrical From scratch: alternator wiring
  • fox racer v2
  • Jun 23, 2025
  • Fox 5.0 Mustang Tech
Replies
0
Views
527
Fox 5.0 Mustang Tech Jun 23, 2025
fox racer v2
F
D
Electrical Need some Altenator wiring help please.
  • DanB93
  • Feb 3, 2025
  • Fox 5.0 Mustang Tech
Replies
6
Views
516
Fox 5.0 Mustang Tech Apr 7, 2025
Rcdgl
R
Drivetrain 83’ Glx convertible C5 Trans help!
  • JacksonJared2113
  • Dec 25, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
330
Fox 5.0 Mustang Tech Dec 26, 2025
JacksonJared2113
A
Electrical Help Identify wires/connections engine bay passenger side firewall (unused)
  • afjLX
  • Dec 4, 2024
  • Fox 5.0 Mustang Tech
Replies
8
Views
1K
Fox 5.0 Mustang Tech Dec 10, 2024
afjLX
A
82 Gen 1 Coyote Swap AC Questions...
  • thinkfaster
  • Aug 14, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
1
Views
296
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 15, 2025
thinkfaster
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?